Ford says that the base engine will remain a 3.7-liter V-6 that will produce at least 300 hp and 270 lb-ft of torque, paired with either a six-speed manual gearbox or an optional six-speed automatic transmission with paddle shifters.

Unlike its hybrids, however, fuel efficiency is hardly at the top of the list for Mustang buyers. It's a nice-to-have, but not a deal-breaker.

Our guess: 25+ mpg combined

And Ford's only improving the gas mileage because it has to do so for all its cars under the Federal gas-mileage mandate. Which is why it's at least "considering" alternative powertrains--diesel, hybrid, even electric--for Mustangs of the future.

So we're curious to see just how high the 2015 Mustang's ratings can go.

We'll take a stab here and suggest that the base V-6 car could reach 25 mpg (21 city, 33 highway) and the EcoBoost will be marginally higher than that.

The EPA ratings for the 2015 Ford Mustang, along with final powertrain specifications, options, and pricing, will be released much closer to the on-sale date, which will be toward the end of 2014.